The effects of acute and chronic microwave (2.45 GHz, CW) exposure on in vivo membrane models will be examined under a variety of time/dose-response relationships. The increase in blood-brain barrier (BBB) and maternal/placental (M/P) unit permeabilities in mice following acute microwave exposure will be contrasted to the decrease observed in the canalicular membrane permeability of the rat. The increased permeability of the BBB and M/P unit will be examined with alterations in drug uptake studies (barbiturate sleeping times, apparent pA2 values for agonist/antagonist interactions, BUI's, and PA values) and changes in neurotoxicity of Japanese Encephalitis Virus (JEV). The decreased permeability of the rat canalicular membrane will be measured using an SRII technique which also allows quantitation of bile flow rate, intrabiliary pressure and active/facilitated transport systems. The immunologic effect of microwave exposure will be examined by observation of changes in JEV neurotoxicity, thought to be due to changes in CNS micro-pinocytotic activity. Additional studies associated with alterations in interferon's inducibility, CNS availability and eventual systemic clearance, after microwave exposure, will be conducted. An attempt will be made to establish non-thermogenic effects of microwave exposure in those in vivo membrane models which demonstrate sufficient sensitivity. At a molecular level, a newly developed in vivo electron spin resonance (ESR) technique will measure changes in luminal membrane fluidity of cortical and retinal capillaries. This technique may permit a direct evaluation of membrane characteristics as the organism adapts to acute and chronic microwave exposures. Thus, the most probably site of microwave energy interaction with biological systems, the bimolecular membrane, will be investigated with 3 in vivo membrane models which demonstrate a wide spectrum of responses to microwave exposure. Each model has significant health-related implications, as demonstrated by the changes in JEV neurotoxicity and interferon tissue levels following microwave exposures. Finally, a newly developed ESR technique will be utilized to investigate possible mechanisms of microwave induced alterations in membrane function at a molecular level.